No further action was brought by police but details of the web conversations were sent on to Chetham’s.

Dr Preston told a professional conduct hearing of the National College for Teaching and Leadership that his conversations were ‘nothing more than a benign fantasy’ and ‘mere banter’.

He added he would never actually behave towards young teens in the way he discussed.

Inappropriate messages were sent over the course of two web chats in October and November 2013 - around the same time he joined Chetham’s School of Music.

The NCTL panel banned Dr Preston from teaching indefinitely.

Imposing the ban, Jayne Millions of the NCTL, said: “There is no evidence of pupils being affected or harmed by Dr Preston’s conduct.

“However, this case discloses sexual misconduct of a serious nature by a member of the profession. There can be few more damaging considerations for a teacher than to assert, in the way that has occurred in this case, a sexual interest in children of school age.

“Whilst the panel acknowledges that Dr Preston has a previously good record as a teacher, I also note that the panel found Dr Preston demonstrating a disrespectful and repellent attitude to young people.

“I agree with the panel’s view that this is fundamentally inconsistent with him remaining a member of the teaching profession.”

Speaking outside his home in West Yorkshire, Dr Preston refused to discuss details of the case.

A spokeswoman for the school, said: “Chetham’s has nothing to add to the NCTL report other than to confirm that the school followed all the correct procedures and referred Dr Preston to the NCTL.

“Dr Preston was suspended immediately upon arrest and was dismissed from Chetham’s after due process.”

In recent years, dozens of former pupils have contacted police to report historic allegations of abuse against former Chetham’s staff in the 1970s, 80s and 90s.

The school’s former music director Michael Brewer and his ex-wife Hilary were convicted in March 2013 of indecently assaulting ex-pupil Frances Andrade more than 30 years ago.

Mrs Andrade killed herself a week after giving evidence.

Former teachers Nicholas Smith and Duncan McTier have also admitted sexual assaults against former pupils.

Violin teacher Chris Ling - who was to face charges relating to his time at the school - shot himself dead as US police tried to arrest him last year.